In a semiconductor device having a MOSFET as a switching element, it has been known to set a clamp voltage of a drain-to-source voltage Vds to a level equal to or higher than a surge voltage, which is represented by load dump, so as to keep an off state of the MOSFET to thereby restrict breakdown of the element.
However, when the drain-to-source voltage Vds is clamped at a relatively high voltage, which corresponds to the surge voltage, during a protection operation or the like in an overcurrent detection, the electric power consumption during the protection operation is likely to increase. Also, heat is generated due to the large amount of power consumption. Further, since the element has been reduced in size, the increase in the heat generation amount due to the increase in the drain-to-source voltage Vds is notable, as compared with a conventional element.
JP 2001-85618 A discloses a semiconductor integrated circuit that is capable of varying a clamp voltage. In the semiconductor integrated circuit, the clamp voltage is increased in a case where the high surge voltage is assumed, and is decreased in a case where the element needs to absorb high energy for a short time, which is represented by a short-circuit of a load. In the semiconductor device, therefore, the power consumption when the element absorbs the high energy can be reduced, and the amount of heat generation can be reduced.